If you would like to sell magazines in your iOS App you will need to create an in-App purchase in your Appstore connect account, for each magazine that needs to have a price tag attached.
The steps to create an In-app purchase in Appstore connect are as follows:
Login to Appstore connect with your Username (Apple ID) and Password
Click on the "My Apps (Meine Apps)" button
3. Choose the App you would like to have in-App purchases and open the App by clicking on the icon.
4. In the following window choose the "Features" tab located in the upper left corner.
5. On the next window click on the "+" Symbol next to "In-App purchase (In-App Käufe)"
6. The next window lets you specify the type of the in-App purchase you would like to create:
For a single In-App purchase you can choose the item to be either a consumable or non-consumable item (Verbrauchsartikel / Nicht - Verbrauchsartikel).
Consumable Items will need to be purchased again after it has been used once
Non-consumable items will be available for an indefinite time after the purchase has been completed and can be reactivated if the App has been deinstalled previously
Choose the type of the in-App purchase by selecting the respective option and clicking the "select" button in the lower right corner.
7. The next step requires you to fill out various data:
The first entries will require you to fill in a reference name (Verweisname) and a product ID (Produkt-ID) for your in-App purchase.
The reference name is the title associated to the respective in-App purchase in iTunes connect, it will not be referenced in the App Store and in the app itself
This ID is used to mark the respective magazine as in-App purchase inside your App. The Product-ID can consist of letters (upper and lower case A-Z), numbers (0-9) and underscores ( _ ).
Attention: Product IDs are unique and cannot be altered again once the in-App purchase has been created.
After entering the reference name and Product ID of your in-App purchase activate the checkbox labeled "availability (Verfügbarkeit)", to mark the In-App purchase as activated after the successfull review process.
The next tab labeled "Price Tier (Preisgestaltung)" is used to set the price for the in-App purchase. Apple is using a tier system to determine the price for the respective product. To set a price for your in-App product click on the drop down menue and select the desired price. Please note that a price tier of zero equals a product that is free of charge.
After setting up the price tier for your in-App purchase you can move on to the next tab labeled "App Store-information" and the entries presented shown under "Localisation (Lokalisierungen)"
By clicking on the "+" button next to localisation you can choose the language that will be associated with this product. It is possible to select more than one language for the product.
Next to the localisation you will find two entries, one for the display name of the in-App product and one for the description of the in-App product.
The display name will show the name of the sold product. This name is displayed in your app and is visible to your customers.
The desciption field allows you to describe the product you are selling. The description is also displayed in your app and is visible to your customers.
After filling out the "App Store-Information" the last entry that needs to be filled out before your in-App purchase can be saved is found under the reviewnotes (Prüfinformationen) tab.
Adding a description to the textfield is not mandatory to proceed, however a screen shot taken from the app which will make use of the in-App purchases needs to be uploaded.
After entering the necessary information in the required fields, click on the save button in the upper right corner of the screen to save the in-App purchase.
These steps need to be repeated for every in-App purchase you would like to add to your iOS App.
Learn how to activate an In-App-Purchase at yumpu here